Some 24 000 Eritrean refugees are trapped in two camps in Ethiopia's Tigray region, cut off from humanitarian aid, and their food rations may have run out, the United Nations said on Tuesday.

Appealing for access to the Mai Aini and Adi Harush camps, the UN refugee agency said there was "a real danger of hunger" if the refugees did not receive supplies.

Fighting that began between the Ethiopian central government and the Tigray People's Liberation Front (TPLF) last November has escalated in and around the camps, and two refugees have been killed this month, it said.

"The last food distribution to the two refugee camps was done during the month of June, the ration supplies then were only enough for 30 days," Babar Baloch, spokesperson of the UN High Commissioner for Refugees (UNHCR), told a news briefing.

"There is a real danger of hunger among these refugees if supplies do not resume as they may have already run out of food supplies that were given to them."

Clean drinking water is also running out, he said.

David Beasley, head of the World Food Programme, said on Twitter the UN agency would run out of food in Tigray on Friday and that 170 trucks carrying food and other supplies were currently unable to reach them.

An official state website said a unilateral government ceasefire aimed at enabling humanitarian aid was being hampered by TPLF "provocations". It called for pressure on the rebel group to open the route for cargo.

Fadela Chaib, spokesperson of the World Health Organization, said medical services in Tigray were "alarmingly limited", leaving hundreds of thousands of people, including the wounded, without access to basic care.

There has been a "significant and worrisome increase" in cases of severe acute malnutrition reported among children in Tigray, she said.

UNHCR lost access to the camps on July 14, Baloch said.